As a curing agent exhibiting low-temperature fast-curing activity for an epoxy resin, a micro-encapsulated aluminum chelate latent curing agent has previously been proposed in which an aluminum chelating agent is held in a porous resin obtained by subjecting a polyfunctional isocyanate compound to interfacial polymerization (Patent Document 1). Furthermore, a thermosetting epoxy resin composition in which a silane coupling agent, which has a polymerizable group such as a vinyl group and a trialkoxy group that acts as a hydrolyzable group to form a hydroxyl group by hydrolysis, and an epoxy resin are blended in this aluminum chelate latent curing agent, has excellent storage stability, despite it being a one-component type. In addition, such a thermosetting epoxy resin composition has the property of low-temperature fast curing by cationic polymerization (in the same Patent Document).